Nanosilver/poly(DL-lactic-co Glycolic Acid) For The Enhancement Of Antibacterial Properties And Osteoinductivity

BackgroundDespite titanium(Ti)implants have been commonly used in the medical device field due to their superior biocompatibility,implant associated bacteria infection remains a major clinical complication following invasive orthopedic surgery.Prevention of implant-associated infection could be accomplished by coating Ti implants surfaces with antibacterial or anti-adhesive material to inhibit the bacterial biofilm formation on the surfaces of implants.Nanosilver,an effective antibacterial agent against a wide spectrum of bacterial strains,with a low-resistance potential,have attracted much interest to fight infections.Incorporation of nanosilver on Ti implants surface may be a promising approach to prevent biofilm formation.PurposeThe objective of the present study was to investigate the antibacterial effects and osteoinductive properties of nanosilver/poly(DL-lactic-co glycolic acid)(PLGA)-coated titanium(NSPTi)through in vitro and in vivo studies in rabbits.MethodsNanosilver/PLGA coatings were obtained by solvent casting.Gram-positive methicillin-resistant Staphylococcus aureus(MRSA)and the Gram-negative opportunistic pathogen Pseudomonas aeruginosa(PAO-1)were used to evaluate the antibacterial activity of NSPTi implants through the analysis of bacterial colonization in vitro and in vivo.Furthermore,we examined the osteoinductive potential of NSPTi implants in vitro by investigating the proliferation and differentiation of MC3T3-E1 preosteoblast cells.In vivo,the osteoinductive properties of NSPTi implants were assessed by radiographic and three-dimensional computed tomography scanning analysis,hematoxylin and eosin(H&E)staining,and Masson's trichrome staining.ResultsAnalysis of bacterial colonization in vitro showed that bacterial adhesion to the 2%-NSPTi was significantly inhibited,and less than 1%of adhered bacteria survived after 24 h.Analysis of bacterial colonizations in vitro showed that the average colony-forming units(CFU)/g ratios in the 2%-NSPTi with 103 CFU MRSA or PAO-1 werel.50±0.68 and 1.75±0.6,respectively.In the uncoated Ti groups the ratios were 1.03±0.82x103 and 0.94±0.49x103,respectively.Bacterial colonization in 2%-NSPTi group was significantly lower than the uncoated Ti group(p<0.05).These antibacterial test results demonstrated that NSPTi implants had prominent antibacterial properties.Proliferation of MC3T3-E1 cells on the 2%-NSPTi sample was 1.51,1.78,and 2.22 times of that on the uncoated Ti control after 3,5,and 7 days incubation,respectively.Furthermore,NSPTi implants promoted the maturation and differentiation of MC3T3-E1 preosteoblast cells in vitro(on day 21,matrix mineralization of MC3T3-E1 cells on the 2%-NSPTi samplewas 2.15 times greater than the uncoated control Ti)with no cytotoxicity.In vivo experiments showed NSPTi implants accelerated the formation of new bone while suppressing bacterial survival in infected tibial canals of rabbits.ConclusionOur research indicates that NSPTi implants have simultaneous antimicrobial and osteoinductive activities and therefore have potential in clinical applications.